The present invention relates broadly to torque transmitting bearing assemblies particularly adapted to applications for members mounted for relative longitudinal movement.
More specifically, the present invention relates to a bearing application in an assembly wherein a shaft is axially slidable by means of a roller bearing in a housing, the roller bearing provided with at least one bearing race plate which is radially adjustable by means of a housing screw and is adjustably arranged by means of a corresponding row of balls against the bearing race groove running axially in the shaft. The present invention provides means for automatically aligning the bearing race plate in order to prevent a negative effect on the properties resulting from finishing tolerance inaccuracies produced during installation. Specifically, the invention comprises a cupped point arranged on the outer terminal end of the housing screw which penetrates a plastically deformable insert of the bearing race plate during the adjustment of the bearing race plate to achieve automatic alignment thereof.
Bearing arrangements of this type are not new per se. For example, in German Preliminary Application No. 2,849,758, a convex conical or truncated conical surface is machined in the radially slidable bearing race plate and a corresponding but concave constructed conical or truncated conical surface is formed on the outer terminal end of the housing screw. In this manner, the bearing race plate may be adjusted through the housing screw and the bearing race plate is fixed axially and in a peripheral direction by means of the coacting conical surfaces. Thus, the bearing arrangement is capable of transmitting torque. It has been found, however, that the conical surfaces produce a predetermined form-fit contact so that with finishing tolerances, a tilting or offsetting of the bearing race plate must be anticipated especially when the housing screw is not aligned with the center line of the bearing race plate or with the bearing race groove in the shaft. By reason of this, it has been observed that there is undesirable play or poor running properties resulting from these defects so that these assemblies fail prematurely. A specific disadvantage results in applications where two bearing race plates are used for the transmission of torque. For example, in order to obtain a uniform distribution of the torque to both bearing race plates, the individual components or parts must be produced and installed without tolerance leeways. This is hardly possible and in practice is not feasible.
In accordance with another known prior art spindle arrangement shown in Swiss Patent No. 543,683, a roller bearing for the rotating shaft is fixed in the housing by means of a tension screw. In order to equalize axial play, a soft elastic material is introduced in a groove in the outer ring in which the centrally arranged portion of the tension screw presses. The spindle, however, is not intended for the transmission of torque and this patent does not concern itself with a bearing application for longitudinal movements.
With the foregoing in mind, it is therefore an object of the present invention to provide a bearing application for longitudinal movements wherein the individual parts of the assembly are formed with normal dimensional tolerance leeways contributing to economical production thereof and which is capable of being adjusted without causing a tilting or offsetting of the torque transmitting bearing race plates. Additionally, in application where two or more torque transmitting race plates are employed, a uniform load distribution can be obtained very simply and effectively. This is achieved by providing a layer of a plastically deformable material on the side of the bearing race plate confronting the terminal end of the housing screw and utilizing a screw with an axially acting cupped point as a housing screw.
By this arrangement, when adjusting the bearing race plate by means of the housing screw, a light contact takes place initially between the cupped point and the plastically deformable material of the race plate. As a result, the bearing race plate is moved smoothly against the row of balls and therefore against the bearing race groove of the shaft. During the initial contact between the shaft, row of balls, and bearing race plate, the bearing race plate is axially aligned relative to the bearing race groove and in a peripheral direction. This then is the optimum position of the bearing race plate. Upon further turning of the housing screw radially inwardly, this optimum position is retained and the cupped point of the housing screw penetrates the plastically deformable material on the surface of the bearing race plate so that the plate is fixed in all directions and now is capable of transmitting a torque. The plastic deformable material may, for example, be a metal, such as tin, aluminum, copper or the like or may be a plastic material. It is also within the scope of the invention that the appropriate side of the bearing race plate is constructed of a softer material. In applications utilizing two bearing race plates, adjustment of a second bearing race plate takes place similarly so as to produce an automatic alignment to the corresponding race groove in the shaft. A uniform distribution of the torque to both bearing race plates is therefore advantageously guaranteed in both rotational directions. Finishing tolerances of the individual parts are not a criteria and do not adversely effect the alignments since the contact surface, that is, the adjusting surface and the bearing race plate is not predetermined and is advantageously used only after the automatic, individual alignment of the race plate as a result of penetration of the cupped point of the housing screw therein.
In accordance with another embodiment of the present invention, the bearing race plate has adjacent the housing screw, a cup-shaped recess filled with a plastic deformable material. Consequently, the plastically deformable material can be easily applied that is by insertion or a pouring operation. The sidewalls of the cup-shaped recess may comprise for example, a shallow bore to confine the plastically deformable material so that a reliable torque transmission results.